The present invention relates to machines for the application of one-piece or composite articles of hardware to sheet- or web-like workpieces, for example, to pieces of textile material which constitute or can be converted or assembled into jeans, jackets and/or other types of garments. Examples of such machines are presses which can be used to apply rivets, clamps, eyelets, hooks, buttons and/or other metallic or plastic articles of hardware to garments or the like so that the applied articles serve a decorative and/or utilitarian purpose.
Many presently known riveting presses employ a platform or analogous means for supporting a selected portion of a piece of textile material or another flexible and penetrable workpiece in a given plane, e.g., in a horizontal plane above a lower tool and below a vertically reciprocable upper tool which is in register with the lower tool. A component of an article of hardware is attached to the portion of the workpiece on the platform in response to downward movement of the upper tool. Alternatively or in addition to the just outlined mode of attachment, a component of an article of hardware can be placed onto the lower tool and is then affixed to the workpiece in response to downward movement of the upper tool. If two components of an article of hardware are to be applied in a simultaneous operation, one of these components penetrates through the workpiece on the platform and is united with the other component. For example, a hollow rivet can be assembled of a first component having a first head and a shank and of a second component having a second head and a sleeve for reception of the shank. Parts of snap fasteners can be affixed in similar fashion, the same as many other articles of small hardware, e.g., rows of buttons next to a selected marginal portion of the workpiece.
If a component of an article of hardware is to be attached to the workpiece from above, such component is held at a level below the vertically reciprocable upper tool by a set of grippers which can yield when the upper tool descends so that the component is disengaged from the grippers and is applied to the workpiece on the platform. The grippers receive successive components of articles of hardware from a suitable magazine by way of a chute and a pusher which latter causes successive components to advance along a relatively short path extending from the discharge end of the chute to the space between the grippers. The grippers are thereupon caused to descend in order to place the freshly received component to a desired position with reference to the portion of the workpiece on the platform, and the upper tool also descends, normally at a rate which is different from that of descent of the grippers, to disengage the component from the grippers and to apply it to the workpiece not earlier than when the component is adequately positioned with reference to the material on the platform.
German Offenlegungsschrift No. 29 15 328 discloses a riveting press of the above outlined character wherein the grippers for the components of articles of hardware simultaneously constitute parts of a safety device which protects the hands of the operator from injury by preventing the prime mover from starting a working cycle when an obstruction (e.g., a finger) is located between the grippers and the workpiece on the platform. Thus, the provision of grippers is desirable and advantageous for several reasons.
A drawback of presently known riveting presses and analogous machines of the above outlined character is that a workpiece which consists of or contains a textile or other foldable and hence deformable material is likely to be wrinkled during placing of a selected portion of such workpiece onto the platform below the vertically reciprocable tool as well as that the grippers themselves are likely to cause the workpiece to develop wrinkles, pleats and/or other irregularities which detract from the appearance of the finished product and/or prevent the application of articles of hardware to predetermined portions of the workpiece. Moreover, the development of wrinkles can affect the reliability of connection between the components of an applied article of hardware and/or the connection between the one and/or the other component of such article of hardware and the workpiece.